GE U50

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GE U50
UP U50 50.jpg
U50 #50 on an eastbound freight at Laramie, Wyoming.
Type and origin
Power type Diesel-electric
Builder General Electric
Model U50
Build date 1963 - 65
Total produced 26
 • AAR B+B-B+B
Gauge 4 ft 8 12 in (1,435 mm)
Trucks 4
Length 83 ft 6.5 in (25.46 m)
Prime mover Dual GE FDL-16
Engine type Diesel
Traction motors 4
Transmission Diesel electric
Performance figures
Power output 5,000 hp (3,700 kW)
Operators Union Pacific Railroad
Southern Pacific Railroad
Nicknames Baby Hueys
Locale North America
Disposition scrapped

The GE U50 was an eight-axle, 5,000 hp (3.7 MW) diesel-electric locomotive built by GE Rail. They were twin-engined locomotives, combining two 2,500 hp (1,900 kW) diesel engines.


The U50 rode on four two-axle trucks, grouped in pairs linked by span bolsters, giving a wheel arrangement of B+B-B+B. The trucks and bolsters were re-used from scrapped UP turbine locomotives built by GE during the 1950s. The U50 was built in response to the Union Pacific Railroad's requirement, issued in the early 1960s, for a 15,000 hp (11,200 kW) 3-unit locomotive intended to replace the turbines. The design was effectively two U25B locomotives on a single frame; each diesel engine and generator powered only the two trucks at the same end. Three were delivered to the UP in October 1963, and three to the Southern Pacific Railroad in May and June 1964. Other locomotives built to this requirement were the EMD DD35 and the ALCO Century 855.

The Southern Pacific kept the three but did not order any more. They were kept on the roster until the late 1970s, but were often sidelined. SP's units gained the nickname "Baby Hueys" from the cartoon character of the same name.[1] Original numbers were #8500-8502; they were later renumbered #9950-9952. Southern Pacific's three units differed from the Union Pacific U50s by having a cab door and headlights in the hood beneath the front windows.

The Union Pacific was more satisfied with their three, and ordered 20 more. A batch of 12 were delivered between July and September 1964, while a final eight were built May through August 1965. They were numbered #31-53. UP #52 was delivered with a Cummins PT fuel system and rated at 5600 horsepower. The #52 had a standard fuel system installed in October 1966 and was rerated to 5000 horsepower.

Twenty of the Union Pacific U50s were withdrawn from service in 1973 and 1974 and traded-in to GE for U30Cs. The last three Union Pacific units remained on the roster until April 1977. The Southern Pacific's three survived in service until 1977.

The U50 is sometimes inaccurately referred to as the U50D, a back-formation from the U50C name given to the six-axle units. The name is incorrect and was never used by the manufacturer or the railroad. The U50 did not ride on D trucks in any case. It is also sometimes referred to as the U50B,[2] but this is incorrect as well. Some[who?] references erroneously give the wheel arrangement as B-B+B-B.

See also[edit]


  1. ^ My Espee Modelers Archive U50 Information Page
  2. ^ The Great Book of Trains by Brian Hollingsworth, Salamander Books Ltd. (UK) 2003 p.323